A pilot study indicated that the plasma concentration of n-acetyl neuraminic acid, NANA, (liberated after acid hydrolysis) was increased in a series of 15 cancer patients. The concentration of NANA was not elevated in 10 volunteers or in 3 patients with suspected cancer. The range of NANA values for the normal volunteers (and 3 cancer suspects) was 516-786 ug NANA/ml plasma. The values for the cancer patients range from 821 to 1830 ug NANA/ml. The values seemed especially high in patiends with Ca of the lung. We plan to measure plasma NANA concentrations for a large number of patients: 1) with known or suspected cancer, 2) with diseases (not cancer) which may interfere with the results; eg. Rheumatoid arthritis, Cirrhosis, Tuberculosis, Renal failure, etc., and 3) normal volunteers. We plan to correlate the results with: 1) the presence or absence of cancer, 2) the anatomic site of the primary, 3) Histologic type (and grade), 4) extent of the disease, 5) relationship to therapy (that is, with the patient's status at the time he returns for follow-up visits).